[ntuple] Remove unnecessary memcpy from test
[ntuple] Remove unnecessary memcpy from test

Also add comment about offsets starting from 0 implicitly

olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root